1. Field of the Invention
The present invention relates to an image capture apparatus using a solid-state image sensor.
2. Description of the Related Art
In conventional image capture apparatuses using a solid-state image sensor, an image signal output from the image sensor and pulses for driving the image sensor are generated in circuitry. In addition, various pulses for signal processing are mixed in the image sensor. These pulses are produced from a common reference clock signal and are frequently synchronized with one another. If high-frequency components of such synchronized signals are mixed in with the image signal through capacitive coupling between wiring patterns or the like in the apparatus, then visible line- or point-like fixed pattern noise will occur on the image based on the image signal. This fixed pattern noise may cause degradation of image quality.
Accordingly, an image capture apparatus has been proposed which is adapted to, at the time of continuous shooting, capture a series of images which are displaced relative to one another in position of the same subject by a predetermined amount by rotating a mirror that transmits a subject image to a two-dimensional photo-sensor in uniform angular steps and then combine the captured images with reference to a specific subject image on each captured image to create a composite image (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-214662).
According to this conventional image capture apparatus, the rotation of the mirror causes the positional relationship between the particular subject image as the reference for combining the captured images and the fixed pattern noise to vary for each captured image. Therefore, the fixed pattern noise which occurs on each captured image can be scattered on the composite image to reduce the effect of the pattern noise on the composite image.
With the conventional image capture apparatus, however, in the event that the hands of a user shake during continuous shooting, the positional displacement of the subject image on the captured images based on the rotation of the mirror may be negated. In that case, the positional relation between the particular subject image and the fixed pattern noise would be the same for the captured images. That is, in the event of a hand shake or a camera-shake, even if the captured images are combined, the conventional image capture apparatus may fail to scatter the fixed pattern noise on the composite image.